U.S. patent application number 09/998621 was filed with the patent office on 2002-12-26 for sealing element, hemetic container and sealing method thereof.
This patent application is currently assigned to Shin-Etsu Polymer Co., Ltd.. Invention is credited to Azuma, Yoshio, Fujimori, Yoshiaki, Horita, Naohiro, Nishimura, Yasuyuki, Takahashi, Masato.
Application Number | 20020195455 09/998621 |
Document ID | / |
Family ID | 19015691 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020195455 |
Kind Code |
A1 |
Takahashi, Masato ; et
al. |
December 26, 2002 |
Sealing element, hemetic container and sealing method thereof
Abstract
A fit-holding groove is formed by notching the outer periphery
of a door element to be fitted to close a container body. A sealing
element interposed between the container body and door element is
composed of an endless portion to be fitted into the fit-holding
groove, a protruding part projected from the peripheral corner of
the endless portion, obliquely and outwardly with respect to the
open front of the container body, forming a substantially acute
angle between itself and the contact surface of the open front of
the container body and a pair of fitting ribs projectively formed
on the obverse surface of the endless portion so as to be fitted in
contact with the compartmentalized inner wall of the fit-holding
portion.
Inventors: |
Takahashi, Masato;
(Jouetsu-shi, JP) ; Fujimori, Yoshiaki;
(Itoigawa-shi, JP) ; Azuma, Yoshio; (Arida-shi,
JP) ; Nishimura, Yasuyuki; (Arida-shi, JP) ;
Horita, Naohiro; (Arida-shi, JP) |
Correspondence
Address: |
Peter C. Schechter
Darby & Darby P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
Shin-Etsu Polymer Co., Ltd.
|
Family ID: |
19015691 |
Appl. No.: |
09/998621 |
Filed: |
November 30, 2001 |
Current U.S.
Class: |
220/806 ;
220/378 |
Current CPC
Class: |
Y10S 277/921 20130101;
B65D 53/02 20130101 |
Class at
Publication: |
220/806 ;
220/378 |
International
Class: |
B65D 053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 2001 |
JP |
2001-174401 |
Claims
What is claimed is:
1. A sealing element which is interposed between the opening face
of a fitted element and a fitting element and elastically
deformable so as to prevent leakage from the interior and entrance
from the exterior, comprising: an endless portion; a flexible
protruding part projected approximately obliquely outwards from the
periphery of the endless portion; and a fitting means having a
notch or projection formed on at least one of the obverse and
reverse sides of the endless portion.
2. The sealing element according to claim 1, wherein a rounded
projection is formed at the distal end of the protruding part.
3. The sealing element according to claim 1, wherein the fitting
means comprises a plurality of fitting ribs, and among the
plurality of fitting ribs, the fitting rib located closest to the
entrance side of a fit-holding portion formed on the opening face
of the fitted element or on the fitting element side are higher
than those located on the interior side of the fit-holding
portion.
4. The sealing element according to claim 2, wherein the fitting
means comprises a plurality of fitting ribs, and among the
plurality of fitting ribs, the fitting rib located closest to the
entrance side of a fit-holding portion formed on the opening face
of the fitted element or on the fitting element side are higher
than those located on the interior side of the fit-holding
portion.
5. The sealing element according to claim 1, wherein the protruding
part is set curved inwardly in the direction of squeezing so that
the curved portion of the protruding part comes into contact with
the contact surface of the fitted element or the contact surface of
the fitting element.
6. The sealing element according to claim 2, wherein the protruding
part is set curved inwardly in the direction of squeezing so that
the curved portion of the protruding part comes into contact with
the contact surface of the fitted element or the contact surface of
the fitting element.
7. The sealing element according to claim 3, wherein the protruding
part is set curved inwardly in the direction of squeezing so that
the curved portion of the protruding part comes into contact with
the contact surface of the fitted element or the contact surface of
the fitting element.
8. The sealing element according to claim 4, wherein the protruding
part is set curved inwardly in the direction of squeezing so that
the curved portion of the protruding part comes into contact with
the contact surface of the fitted element or the contact surface of
the fitting element.
9. A hermetic container comprising: a container body having an
opening face; a door element to be detachably fitted to the opening
face of the container body; and an elastically deformable sealing
element interposed between the opening face and the door element,
characterized in that a fit-holding portion is formed by notching
either the inner periphery of the opening face of the container
body or the outer periphery of the door element, and the sealing
element comprises: an endless portion to be fitted into the
fit-holding portion; a flexible protruding part projected from the
endless portion, obliquely and outwardly with respect to the
opening face of the container body, forming a substantially acute
angle between itself and the contact surface of the door element or
the contact surface of the opening face of the container body; and
a fitting means having a notch or projection formed on at least one
of the obverse and reverse sides of the endless portion and fitted
in contact with the compartmentalized inner wall of the fit-holding
portion.
10. The hermetic container according to claim 9, wherein the
sealing element is formed using a fluororubber composition.
11. A sealing method of a hermetic container, for sealing a
hermetic container using a container body having an opening face, a
door element to be detachably fitted to the opening face of the
container body, a fit-holding portion formed by notching either the
inner periphery of the opening face of the container body or the
outer periphery of the door element and an elastically deformable
sealing element fitted in the fit-holding portion and interposed
between the container body and the door element, characterized in
that the sealing element is comprised of an endless portion to be
fitted to the fit-holding portion, flexible protruding part
extended from the endless portion and a fitting means having a
notch or projection formed on at least one of the obverse and
reverse sides of the endless portion and fitted in contact with the
compartmentalized inner wall of the fit-holding portion, the
protruding part of the sealing element is extended approximately
obliquely and outwardly with respect to the opening face of the
container body so as to form a substantially acute angle between
itself and the contact surface of the door element or the contact
surface of the opening face of the container body, and the
protruding part of the sealing element is curved outwards with
respect to the opening face of the container body to establish
sealing when the door element is closed.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a sealing element, hermetic
container and its sealing method for keeping contamination-averse
items clean. More detailedly, the present invention relates to a
sealing element, hermetic container and its sealing method to be
used for accommodation and shipment of contamination-averse
precision substrates such as semiconductor wafers, masking glass
plates, liquid crystal cells, recording media, etc., and to be used
for positioning precision substrates to processing machines which
shape and process the substrates and for transportation and storage
of them between processing machines.
[0003] (2) Description of the Prior Art
[0004] There are a variety of types of plastic storage containers
for accommodating contamination-averse items. As one example,
hermetic containers used for production of semiconductor parts can
be mentioned. Large-diametric development(e.g., 300 mm or 400 mm or
greater) of precision substrates used for fabrication of
semiconductor parts, such as semiconductor wafers, masking glass
substrates etc., has been discussed and demanded, aiming at
reduction in cost by improving the production yield of
semiconductor substrates, as price competition of semiconductor
devices has become more severe. At the same time, semiconductor
circuits have become more and more miniaturized. For example, the
design rule (the minimum line width in processing) of DRAMs
(dynamic random access memory) has been being shifted from 0.25
.mu.m to 0.18 .mu.m or less. Needless to say at the factories where
semiconductor substrates are processed, there have been demands for
high cleanness of the containers which are used to store
semiconductor substrates when transported.
[0005] In order to meet such demands, a method, called `SMIF` in
abbreviation, has been proposed, which assures highly clean
surroundings within limited, local spaces required for fabrication
of semiconductor substrates and hermetically keeps a plurality of
semiconductor substrates clean in a hermetic container so as to
transport the hermetic container between several clean
environmental spaces. To realize this method, development of
hermetic containers which can be automatically conveyed without
letting the precision substrates therein be contaminated and may
allow itself direct access to the processing equipment is in
progress.
[0006] As partly shown in FIGS. 1 and 2, a conventional hermetic
container is comprised of a container body 1 having an opening on
the front, a door element 11 detachably fitted to open and close
the open front 9 of the container body 1 and a sealing element 20
interposed between the container body 1 and door element 11 for
keeping the inside clean. This sealing element 20 may be a squeeze
type made up of an O-ring having a circular section or a type shown
in FIGS. 1 and 2.
[0007] The sealing element 20 of this type is formed of an endless
molding of a material selected from various types of rubbers or
elastomers. This sealing element 20, as shown in the same figures,
is configured of a deformable endless portion 21 fitted into a
fit-holding groove 16 formed on the outer peripheral side of door
element 11, a recessed portion 25 of an approximately rectangular
section, formed on the underside closer to the outer periphery of
the endless portion 21 to create a clearance relative to door
element 11, and a deformable rib 26 projected perpendicularly at
the obverse surface on the outer peripheral side of endless portion
21 so as to come into contact with the inner periphery of the open
front of container body 1.
[0008] When door element 11 is fitted to the open front 9 of
container body 1 with a multiple number of precision substrates
aligned and stored therein, this sealing element 20, especially
part of endless portion 21 and rib 26 having a pin-like cross
section, deform while recessed portion 25 adjusts the compressive
force, to thereby totally seal the open front of container body
1.
[0009] Since, in the conventional hermetic container, sealing
element 20 is formed of a mere molding of a rubber or elastomer,
which cannot afford the necessary dimensional accuracy and the
necessary deformability, it becomes markedly difficult, as the size
of the opening of container body 1 becomes greater, to secure
hermetic confinement by making sealing element 20 into uniform
contact with the inner periphery of the open front. Particularly,
the sealing element reveals marked deterioration of its sealing
ability at the corners of open front 9 of container body 1, due to
pressures in two different directions and its dimensional
errors.
[0010] The above problem can be solved by making sealing element 20
undergo a greater amount of squeezing. However, upon
standardization of the specifications of the device for opening and
closing door element 11, the pressing force allowed to act on the
opening and closing device of door element 11 is limited by an
upper boundary, in order to protect the device and the hermetic
container. Therefore, if the repulsive force of sealing element 20
exceeds the upper boundary, the repulsive force of sealing element
20 will apply a load greater than necessary on the opening and
closing device of door element 11, causing a risk of interrupting
the operation of door element 11. The sealing element 20 of the
type shown in FIG. 1 presents its sealing function through rib 26,
but this rib 26 can bend either inwards or outwards hence the
direction of deformation is largely unknown, so that if the rib 26
flexes in reverse to the expected direction, the sealability may
become uneven at that portion.
[0011] Further, since in local environments, the precision
substrates should be loaded from the hermetic container for each
processing step and be unloaded after each process, door element 11
of the hermetic container will be repeatedly opened and closed.
Therefore, it frequently happens that sealing element 20 may
displace from the proper position due to repeated opening and
closing actions and be squeezed intensively between container body
1 and fit-holding groove 16 of door element 11 to be deformed
greater than necessary. There is also another problem where
expected sealability cannot be obtained or resin powder or
particles may arise due to local rubbing of sealing element 20 when
open front 9 of container body 1 is closed by door element 11,
contaminating the precision substrates therein.
[0012] Moreover, when the hermetic container is washed in order to
keep it clean, the conventional sealing element 20 has been washed
while remaining fitted on container body 1 or door element 11.
However, when a type of sealing element shown in FIG. 1 is used,
not only is the sealing element not washed thoroughly because
recessed portion 25 cannot be cleaned well, but also there is a
risk that water droplets W might be left over. Therefore, a sealing
element of this type is poor in cleansability and drainage, and
takes a very long time to dry.
SUMMARY OF THE INVENTION
[0013] The present invention has been devised in view of what has
been discussed above, and it is therefore an object of the present
invention to provide a sealing element of a hermetic container,
with which the inner periphery of the opening face of the container
body can be substantially uniformly sealed and it is possible to
prevent items from being contaminated without causing any
interrupts of the automatic opening and closing actions of the door
element and without degradation of sealability due to repeated
opening and closing actions, and which can be cleansed thoroughly
even when washing with the container body or door element, is
excellent in cleansability and drainage and can reduce the time
needed for drying. The present invention also provide a hermetic
container with the sealing element and a sealing method
thereof.
[0014] In order to achieve the above object, the present invention
is configured as follows:
[0015] In accordance with the first aspect of the present
invention, a sealing element which is interposed between the
opening face of a fitted element and a fitting element and
elastically deformable so as to prevent leakage from the interior
and entrance from the exterior, comprises: an endless portion; a
flexible protruding part projected approximately obliquely outwards
from the periphery of the endless portion; and a fitting means
having a notch or projection formed on at least one of the obverse
and reverse sides of the endless portion.
[0016] In accordance with the second aspect of the present
invention, the sealing element having the above first feature is
characterized in that a rounded projection is formed at the distal
end of the protruding part.
[0017] In accordance with the third aspect of the present
invention, the sealing element having the above first feature is
characterized in that the fitting means comprises a plurality of
fitting ribs, and among the plurality of fitting ribs, the fitting
rib located closest to the entrance side of a fit-holding portion
formed on the opening face of the fitted element or on the fitting
element side are higher than those located on the interior side of
the fit-holding portion.
[0018] In accordance with the fourth aspect of the present
invention, the sealing element having the above second feature is
characterized in that the fitting means comprises a plurality of
fitting ribs, and among the plurality of fitting ribs, the fitting
rib located closest to the entrance side of a fit-holding portion
formed on the opening face of the fitted element or on the fitting
element side are higher than those located on the interior side of
the fit-holding portion.
[0019] In accordance with the fifth aspect of the present
invention, the sealing element having the above first feature is
characterized in that the protruding part is set curved inwardly in
the direction of squeezing so that the curved portion of the
protruding part comes into contact with the contact surface of the
fitted element or the contact surface of the fitting element.
[0020] In accordance with the sixth aspect of the present
invention, the sealing element having the above second feature is
characterized in that the protruding part is set curved inwardly in
the direction of squeezing so that the curved portion of the
protruding part comes into contact with the contact surface of the
fitted element or the contact surface of the fitting element.
[0021] In accordance with the seventh aspect of the present
invention, the sealing element having the above third feature is
characterized in that the protruding part is set curved inwardly in
the direction of squeezing so that the curved portion of the
protruding part comes into contact with the contact surface of the
fitted element or the contact surface of the fitting element.
[0022] In accordance with the eighth aspect of the present
invention, the sealing element having the above fourth feature is
characterized in that the protruding part is set curved inwardly in
the direction of squeezing so that the curved portion of the
protruding part comes into contact with the contact surface of the
fitted element or the contact surface of the fitting element.
[0023] In accordance with the ninth aspect of the present
invention, a hermetic container includes: a container body having
an opening face; a door element to be detachably fitted to the
opening face of the container body; and an elastically deformable
sealing element interposed between the opening face and the door
element, and is characterized in that a fit-holding portion is
formed by notching either the inner periphery of the opening face
of the container body or the outer periphery of the door element,
and the sealing element comprises: an endless portion to be fitted
into the fit-holding portion; a flexible protruding part projected
from the endless portion, obliquely and outwardly with respect to
the opening face of the container body, forming a substantially
acute angle between itself and the contact surface of the door
element or the contact surface of the opening face of the container
body; and a fitting means having a notch or projection formed on at
least one of the obverse and reverse sides of the endless portion
and fitted in contact with the compartmentalized inner wall of the
fit-holding portion.
[0024] In accordance with the tenth aspect of the present
invention, the hermetic container having the above ninth feature is
characterized in that the sealing element is formed using a
fluororubber composition.
[0025] In accordance with the eleventh aspect of the present
invention, a sealing method of a hermetic container, for sealing a
hermetic container using a container body having an opening face, a
door element to be detachably fitted to the opening face of the
container body, a fit-holding portion formed by notching either the
inner periphery of the opening face of the container body or the
outer periphery of the door element and an elastically deformable
sealing element fitted in the fit-holding portion and interposed
between the container body and the door element, is characterized
in that the sealing element is comprised of an endless portion to
be fitted to the fit-holding portion, flexible protruding part
extended from the endless portion and a fitting means having a
notch or projection formed on at least one of the obverse and
reverse sides of the endless portion and fitted in contact with the
compartmentalized inner wall of the fit-holding portion, the
protruding part of the sealing element is extended approximately
obliquely and outwardly with respect to the opening face of the
container body so as to form a substantially acute angle between
itself and the contact surface of the door element or the contact
surface of the opening face of the container body, and the
protruding part of the sealing element is curved outwards with
respect to the opening face of the container body to establish
sealing when the door element is closed.
[0026] Next, the effects of the present invention will be
described.
[0027] First, according to the present invention, when the opening
face of a fitted element such as a pipe, cassette, box, mechanical
part, transport container, receptacle, etc., is closed by a fitting
element such as a mechanical part, door element, etc., a sealing
element is fitted to a fit-holding portion such as a fit-holding
groove or the like formed on the fitted element or the fitting
element in such a manner that a protruding part of the sealing
element is directed outwards from the outer periphery of the
endless portion. Then, the fitting element is fitted to the opening
face of the fitted element while the protruding part of the sealing
element is set obliquely outwards with respect to the opening face
of the fitted element, forming a substantial acute angle between
the protruding part or its extension and the contact surface of the
opening face of the fitted element or the contact surface of the
fitting element. In this arrangement, upon fitting, the opening
face of the fitted element can be properly sealed by the fitting
element by making the protruding part of the sealing element deform
outwards with respect to the opening face of the fitted
element.
[0028] According to another aspect of the present invention, when
more than one fitting ribs are formed on the obverse surface of the
endless portion at inner and outer peripheral sites, it is possible
to disperse the retaining force. Accordingly, the retaining force
for each rib can be set to be smaller compared to the configuration
where only a single rib is provided. Therefore, the margin of the
rib to be squeezed can be reduced so as to allow easy attachment.
Further, the sealing element is easy to fit into fit-holding
portion, and yet the sealability is improved.
[0029] Further, according to the present invention, when the
opening face of a container body having items stored therein is
closed by a door element, a sealing element is fitted to the
fit-holding portion of the container body or door element in such a
manner that the protruding part of the sealing element is directed
peripherally outwards. Then, the door element is fitted to the
opening face of the container body while the protruding part of the
sealing element is set obliquely outwards with respect to the
opening face of the container body, forming a substantial acute
angle between the protruding part or its extension and the contact
surface of the opening face of the container body or the contact
surface of the door element. In this arrangement, upon fitting, the
opening face of the container body can be hermetically sealed by
the door element by making the protruding part of the sealing
element deform outwards with respect to the opening face of the
container body.
[0030] Finally, according to the present invention, since the
sealing element is formed of a fluororubber composition, the
sealing element can be formed with high dimensional precision and
also can be deformed relatively easily. Further, it is possible for
fluororubber composition to generally provide excellent heat
resistance, oil resistance, chemical resistance for the sealing
element. Since the amount of vaporization of organic components is
quite low, this makes it possible to avoid the stored items being
contaminated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a partial sectional view for illustrating a
conventional hermetic container and its sealing method;
[0032] FIG. 2 is a partial sectional view for illustrating the
sealing element shown in FIG. 1 being deformed;
[0033] FIG. 3 is an exploded perspective overall view showing the
embodiment of a hermetic container and its sealing method according
to the present invention;
[0034] FIG. 4 is a front view showing a sealing element in the
embodiment of the sealing element, hermetic container and its
sealing method according to the present invention;
[0035] FIG. 5 is a sectional view cut along a plane III-III in FIG.
4;
[0036] FIG. 6 is a sectional view cut along a plane IV-IV in FIG.
4;
[0037] FIG. 7 is a partial sectional illustration showing a state
where a door element with a sealing element fitted thereon is
fitted to a container body of the embodiment of a hermetic
container and its sealing method according to the present
invention;
[0038] FIG. 8 is a partial sectional illustration showing a state
where the protruding part of the sealing element shown in FIG. 7 is
being bent;
[0039] FIG. 9 is a partial sectional illustration showing the
second embodiment of a hermetic container and its sealing method
according to the present invention;
[0040] FIG. 10 is a partial sectional illustration showing the
third embodiment of a hermetic container and its sealing method
according to the present invention;
[0041] FIG. 11 is a partial sectional illustration showing the
fourth embodiment of a hermetic container and its sealing method
according to the present invention;
[0042] FIG. 12 is a sectional illustration showing a sealing
element of the fifth embodiment of a hermetic container and its
sealing method according to the present invention;
[0043] FIG. 13 is a sectional illustration showing a state where
the sealing element shown in FIG. 12 is used to fit the door
element to the container body;
[0044] FIG. 14 is a partial sectional illustration showing a state
where the protruding part of the sealing element shown in FIG. 13
is being deformed;
[0045] FIG. 15 is a partially enlarged illustration showing the
sealing element of FIG. 12;
[0046] FIG. 16 is a sectional illustration showing a sealing
element in the sixth embodiment of a hermetic container and its
sealing method according to the present invention;
[0047] FIG. 17 is a sectional illustration showing a sealing
element in the seventh embodiment of a hermetic container and its
sealing method according to the present invention; and,
[0048] FIG. 18 is a sectional illustration showing one embodiment
of a hermetic container and its sealing method according to the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] Herein, the protruding part extending approximately
obliquely in the description in the present invention may include
that extending exactly obliquely and that extending approximately
obliquely, which means that a curved portion may be partially
included. The rounded projection described herein may include a
projection having an exact circular section and a projection having
an approximately circular section. The fitting rib may be formed to
have a triangular, semicircular, semi-elliptic, semi-oval,
trapezoidal section or other sectional shapes. One or multiple
number of fitting ribs may be provided as appropriate. The
substantially acute angle described herein may include a strictly
defined acute angle and a shape approximating an acute angle. The
opening face of the container body may be arranged at the front, on
the top or on any side face. The door element is formed in an
approximate rectangular, approximate circular, approximate oval
shape or any other shape, conforming to the shape of the opening
face. Further, main contents of the hermetic container are
semiconductor wafers, masking glass substrates, liquid crystal
cells, recording media and the like, but should not be limited to
these. Various kinds of items such as, for example, domestic use
items, mechanical parts, electric and electronic parts,
anti-environmental items and the like may be stored either singly
or plurally.
[0050] Now, the preferred embodiments of the present invention will
be described with reference to the accompanying drawings. The
hermetic container in the first embodiment is constructed, as shown
in FIGS. 3 through 8, such that an approximately rectangular door
11 is detachably fitted to an open front 9 of a front-open box type
container body 1 with an elastically deformable, endless sealing
element 20 interposed therebetween so as to establish hermetic
confinement.
[0051] As shown in FIG. 3, container body 1 is formed of a
transparent or opaque, approximately cubic molding made up of a
synthetic resin such as polycarbonate, polypropyrene or the like,
so as to accommodate a multiple number of circular precision
substrates 2 arranged vertically with a predetermined pitch. This
container body 1 has on its underside V-grooves which are
projectively formed at both sides on the front side and at the
center on the rear side and function as positioning means relative
to unillustrated precision substrate processing equipment. A
plate-like bottom plate 3 is attached to these V-grooves and
detachably supported thereby. This bottom plate is molded as an
approximate Y-shape when viewed from top, made up of two forked
arms arranged at left and right on the front side and one arm
extending to the center on the rear side. Each arm has a guidance
portion 4 formed so as to mate the corresponding V-groove.
[0052] As shown in the same drawing, separate parts such as side
rails 5 and manual handles 6 can be selectively attached in a
detachable manner to left and right side faces of container body 1.
Further, a robotic flange 7, which will be held by an unillustrated
conveyer robot, may selectively mounted in a detachable manner at
the center on the top of container body 1. Formed integrally or
detachably on both inner sides, left and right, of container body 1
are a pair of rack-like supporting portions 8, between which a
multiple number of precision substrates 2 are put horizontally in
alignment with each other with a predetermined pitch. As shown in
FIGS. 7 and 8, open front 9 of container body 1 is formed with a
step, gradually spreading outward toward the exterior of the
container, so that door element 11 can be guided smoothly and
fitted quickly when door element 11 is closed. Dented in the inner
periphery of open front 9 of container body 1 are engagement holes
10 at the right and left, on both upper and lower sides, as shown
in FIG. 3.
[0053] Door element 11 is comprised of inner and outer plates 12
and 13 fitted to and opposing each other with a clearance
therebetween, as shown in FIG. 3. A latch mechanism 14 is built in
between these inner plate 12 and outer plate 13, so that when door
element 11 is fitted to container body 1, this latch mechanism 14
causes retractable engagement claws 15 to project out into
respective engagement holes 10 to establish an air-tight state
inside the hermetic container. As shown in FIGS. 7 and 8, an
endless, indented, fit-holding groove 16 is notched on the outer
peripheral side of door element 11 while passage holes 17 for
engagement claws 15 are formed at the right and left, on both top
and bottom sides of the outer periphery, as shown in FIG. 3. A
rack-like retainer 18 is detachably mounted on inner plate 12 so as
to resiliently support a multiple number of precision substrates 2
by their front rim. A pair of manipulative keyholes 19 for latch
mechanism 14 are formed at both left and right in outer plate
13.
[0054] Sealing element 20 is formed of a molding having a hardness
of about A60/S to A90/S (measured based on JIS K 6253) using a
thermoplastic elastomer, fluororubber, EPDM, NBR or the like. As
the material of this sealing element 20, fluororubber is the most
preferable because it generates a lesser amount of organic gas
components during heating and has the least adverse effect on
precision substrates 2. Sealing element 20, as shown in FIGS. 4 to
6, is comprised of an endless portion 21 having an approximately
rectangular section to be fitted into fit-holding groove 16, a
protruding part 22 which protrudes outwards from the entire
peripheral corner on the outer side of this elastically deformable
endless portion 21 or protrudes obliquely, outwards and toward the
open front of container body 1, forming a substantial acute angle
between itself and the contact face of open front 9 of container
body 1, and a pair of elastically deformable fitting ribs 23 which
are projectively formed, side by side, on the obverse surface close
to the inner periphery of endless portion 21 so as to come into
pressure contact with a compartmentalized inner wall 16a of
fit-holding groove 16.
[0055] As shown in FIG. 4, endless portion 21 is basically formed
in a frame shape with its four corners rounded. Protruding part 22,
as shown in FIGS. 5 and 6, is formed in a tapered configuration
having an approximately triangular section, so that it becomes
gradually narrower from the proximal part toward the distal end.
Specifically, the length of protruding part is set to be 0.5 to 3
times of the width of endless portion 21, more preferably 0.7 to 2
times. In order for this protruding part 22 to produce a beneficial
repulsive force, the proximal part is formed to be 0.4 to 2 mm
thick and the thickness of the distal part is set to be 50 to 80%
of that of the proximal part. Protruding part 22 is extended
obliquely. This angle of inclination of protruding part 22 is set
so as to fall within the range of 10.degree. to 70.degree.,
preferably 25.degree. to 45.degree.,with respect to the line from
the outer periphery of endless portion 21 to the open front 9 of
container body 1.
[0056] Each fitting rib 23, as shown in the same drawing, is formed
to have a semicircular section and so as to be higher by about 1 to
25% than the width of fit-holding groove 16. When endless portion
21 is fitted into fit-holding groove 16, 1 to 25% of the height is
compressed so as to fill the interior space of fit-holding groove
16, which assures firm attachment of the sealing element.
[0057] In connection with this, it is preferred that a vertical
wall or a projection 27 having a vertical wall for positioning
should be formed on the inner side wall of sealing element 20, as
shown in FIG. 5. This projection 27 makes it possible to position
sealing element 20 exactly inside fit-holding groove 16. By the
holding and positioning arrangements, sealing element 20 is
attached exactly inside fit-holding groove 16 while its
displacement can be suppressed, whereby it is possible to seal
fit-holding groove 16 in a preferable manner.
[0058] In the above configuration, when the open front of container
body 1 having a plurality of precision substrates 2 held in
alignment therein is closed with door element 11, sealing element
20 has been fitted beforehand in fit-holding groove 16 of door
element 11 so that protruding part 22 of sealing element 20 is
directed outwards from the periphery. After the arrangement has
been got ready in the above way, door element 11 is fitted to open
front 9 of container body 1 by the precision substrate processing
machine in such a manner that sealing element 20 is held between
container body 1 and door element 11 with its protruding part 22
directed obliquely and outwards with respect to the open front of
container body 1, forming a substantially acute angle between
protruding part 22 or its extension and the contact surface of open
front 9 of container body 1 (see FIG. 7). Then, as latch mechanism
14 is locked by the precision substrate processing machine,
protruding part 22 of sealing element 20 becomes flexed outwards
with respect to the open front of container body 1 (see FIG. 8),
thus making it possible for door element 11 to seal open front 9 of
container body 1, airtightly.
[0059] In the above way, protruding part 22 of sealing element 20
is bent outwards with respect to the open front of container body
1, instead of being compressed in the direction of attachment of
door element 11 (in the vertical direction in FIG. 8). Therefore,
it is possible to markedly reduce the load at the fitting of the
door element. This arrangement also contributes to smooth fitting
of container body 1 and door element 11 hence reduction of troubles
when the door element is opened and closed.
[0060] According to the above configuration, since sealing element
20 can be molded in a simple shape using fluororubber, it is
greatly expected that the sealing element can be formed with high
precision and high flexibility. Therefore, this configuration makes
it quite simple to bring sealing element 20 into uniform contact
with the inner periphery of the open front of container body 1 and
establish necessary sealing. In the present invention, since
protruding part 22 as a part of sealing element 20 is formed in a
tapered shape having a triangular section, the sealing element can
be deformed by a small pressure and also can produce moderate
repulsive force because of its inclination outwards. Therefore, no
marked degradation of sealability will occur even at the corners of
open front 9 of container body 1, for example.
[0061] Further, since it is not necessary for sealing element 20 to
be greatly squeezed, there is no risk of an excessive load being
acted on the opening and closing device of door element 11 by the
repulsive force of sealing element 20 hence it is possible to
effectively eliminate any interruption when door element 11 is
operated. Since protruding part 22 is extended obliquely outwards,
protruding part 22 will not deform either inward or outward.
Therefore, it is possible to prevent protruding part 22 from
flexing in the reverse direction and hence prevent sealing
unevenness which would occur at that portion.
[0062] It is also possible to provide beneficial sealing if a
pressure difference occurs between the interior and exterior of the
hermetic container. For example, suppose that internal pressure of
the hermetic container becomes higher than the external pressure
due to change in temperature or any other reason and internal air
is displaced to the outside. In this case, the internal pressure
acts on protruding part 22 in such a direction to lessen the
flexure of the protruding part, so that air is easily released to
the outside hence the pressure difference can be neutralized within
a relatively short period. In this case, there is no concern of the
interior of container body 1 being contaminated because inner air
flows out from the container body 1. In contrast, when a higher
pressure externally acts on the hermetic container and causes air,
contaminant, etc., to tend to enter container body 1, the
protruding part 22 is pressed further in the direction of the
flexure and enhances the sealability, making outside air difficult
to enter the inside. Accordingly, it is possible to reliably
prevent external air (see the arrow in FIG. 8) from entering the
container and hence contaminating precision substrates 2.
[0063] Moreover, since the sealing element is positioned by a pair
of fitting ribs 23 being squeezed against compartmentalized inner
wall 16a of fit-holding groove 16 so as to make it hard to slip
out, sealing element 20 will not displace from the proper position
even when opening and closing actions of door element 11 are
repeated frequently. Therefore, there is no fear of contamination
of precision substrates 2 by excessive deformation of sealing
element 20 due to being squeezed between container body land
fit-holding groove 20 of door element 11, by loss of sealability,
or by generation of resin power or particles due to local rubbing
of sealing element 20. Further, when in order to keep the hermetic
container clean sealing element 20 is washed while remaining fitted
on container body 1 or door element 11, it is possible to wash the
sealing element thoroughly without leaving any water droplets W
because there is no dented portion such as recessed portion 25 in
the exposed areas of sealing element 20. Accordingly, it is
possible to improve the cleansability and drainage, hence the time
for drying can be markedly reduced.
[0064] Next, FIG. 9 shows the second embodiment of the present
invention. In this case, the contact portion, designated at 9a, of
the open front 9 of container body 1, with sealing element 20, is
formed so as to bulge toward the opening while a flexible
protruding part 22 is projected obliquely and outwards from the
obverse surface close to the periphery of endless portion 21.
Contact portion 9a of container body 1 is formed partly curved near
the stepped portion of open front 9 so as to mate the curved shape
of protruding part 22 when it is bent. This contact portion
approximately opposes the proximal portion of protruding part 22
when door element 11 is closed. Protruding part 22 may be formed so
as to protrude linearly or slightly curved. Other parts are the
same as the above embodiment so the description is omitted.
[0065] With this embodiment, the same operational effects as that
of the above embodiment can be expected. Further, since contact
portion 9a of container body 1 fits the curved shape of protruding
part 22 as being deformed and guides it, it is possible to guide
the protruding part 22 to deform in the correct direction even when
an external pressure acts on the sealing element 20. As a result,
it is apparent that this configuration is able to provide further
improved sealability and protection against contamination of
precision substrates 2.
[0066] Next, FIG. 10 shows the third embodiment of the present
invention. In this case, a flexible protruding part 22 is projected
from the inner peripheral side of endless portion 21 and curved so
as to have a fishhook-shaped section and folded to be extended
obliquely outward while a pair of fitting ribs 23 are formed side
by side on the obverse surface of endless portion 21 close to its
outer periphery. Other parts are the same as the above embodiments
so the description is omitted.
[0067] Also with this embodiment, the same operational effects as
that of the above embodiments can be expected. Further, this
configuration is markedly effective if the above first and second
configurations cannot be used.
[0068] Next, FIG. 11 shows the fourth embodiment of the present
invention. In this case, a fit-holding groove 16 is notched on the
inner periphery of the open front of container body 1 by forming a
compartment wall having an approximately L-shaped section. A
sealing element 20 is fitted into the thus recessed portion, i.e.,
fit-holding groove 16. Other parts are the same as the above
embodiments so the description is omitted.
[0069] Also with this embodiment, the same operational effects as
that of the above embodiments can be expected. Further, this
configuration is markedly effective if the above first, second and
third configurations cannot be used.
[0070] Next, FIGS. 12 through 15 show the fifth embodiment of the
present invention. In this case, a flexible protruding part 22 is
projected obliquely with a slight curvature from the entire
peripheral corner on the outer side of the endless portion 21. This
protruding part 22 is integrally formed at its distal end with a
rounded projection 28 while a pair of fitting ribs 23a and 23b
having substantially triangular sections having different
inclinations from each other are projectively formed, side by side
on the obverse surface close to the inner periphery of endless
portion 21.
[0071] Protruding part 22 is formed so as to be curved toward the
open front of container body 1 with a radius of curvature R of 3 to
10 mm. Rounded projection 28 is preferably formed with a radius of
curvature R ranging from 0.3 to 0.8 mm. Fitting ribs 23a and 23b
are formed to have an inclined surface from the obverse surface
toward the interior side, as shown in FIGS. 12 and 15. The fitting
rib 23a positioned on the obverse surface of endless portion 21 at
the inner side is projectively formed at a smaller height (e.g.,
0.8 mm high) while the fitting rib 23b positioned on the obverse
surface of endless portion 21 at the outer side is projectively
formed to be higher. Other parts are the same as the above
embodiments so the description is omitted.
[0072] Also with this embodiment, the same operational effects as
that of the above embodiments can be expected. Further, rounded
portion 28 is formed swellingly at the distal end of protruding
part 22, instead of forming a linear, knife-edged portion, which is
difficult to mold, the molding process can be markedly simplified.
Since the distal end of protruding part 22 is formed with rounded
projection 28, it is possible to reduce generation of particles
from the distal end of sealing element 20 which repeatedly contact
with container body 1.
[0073] Further, as shown in FIG. 14, since protruding part 22 is
curved inwardly with respect to the compressed direction so that it
will deform along this curved shape (see the arrow in the drawing),
it is possible to markedly reduce the frictional resistance with
container body 1. This makes it possible to reduce the resistance
when the door element is opened and closed, whereby a reliable
sealing can be provided with a small compressing force, leading to
markedly effective suppression of troubles with opening and closing
of door element 11. Further, since fitting rib 23a positioned on
the inner side or the interior side at assembly is formed to be
lower (h1) and fitting rib 23b positioned on the outer side, or the
near to the opening at assembly is formed to be higher (h2), as
shown in FIG. 15, sealing element 20 can be smoothly fitted into
fit-holding groove 16 when it is assembled.
[0074] Still more, as shown in FIG. 15, fitting ribs 23a and 23b
are projected in approximately triangular shapes with their angles
29a and 29b have the relationship: 29a<29b. Therefore, once the
sealing element has been fitted to door element 11, each corner
apex is inclined toward the opening side of fitting groove 16 and
abuts against the wall. As a result, these corner apexes function
like barbs when the protruding part is pulled toward the opening
side, thus making it difficult for the sealing element to come off.
Thus, this configuration provides a structure which prevents the
sealing element from displacing while being used.
[0075] Though latch mechanism 14 is incorporated inside door
element 11 in the above embodiment, this latch mechanism 14 can be
substituted by other engaging mechanisms such as clamps, holding
devices or the like. Further, in the above embodiments,
frame-shaped sealing element 20 has been illustrated, the present
invention should not limited to this. For example, sealing element
20 maybe formed of other shapes such as circular, oval and
polygonal shapes with a vacant center. Endless portion 21 may have
an approximately elliptic cross-section or other shape, instead of
an approximately rectangular cross-section. Further, one or more
projections may be formed on the compartmentalized wall 16a inside
fit-holding groove 16 while one or more notches as the engaging
means may be formed on the obverse surface of endless portion 21 at
the inner and/or outer sides so that these projections and notches
mate each other.
[0076] FIG. 16 shows the sixth embodiment of the present invention.
In this case, a protruding part 22 is projected horizontally from
the entire peripheral side of endless portion 21 and extended
upwards, forming a curved portion. A rounded projection is formed
swellingly at the distal end of the protruding part. A pair of
fitting ribs 23a and 23b having approximate triangular
cross-sections having different inclinations are projectively
formed side by side on the obverse surface at the inner side of
endless portion 21.
[0077] The horizontal portion can be formed at any position on the
outer periphery of the endless portion. The horizontal portion of
the protruding part is 1 to 8 mm long, preferably 1 to 5 mm while
the curved portion is formed sideways above the end so as to have a
radius of curvature R of 1 to 4 mm, preferably 1.5 to 3 mm.
Further, a rounded projection is swellingly formed at the distal
end of the curved portion with its radius of curvature R of 0.3 to
0.8 mm.
[0078] Also in this case, the distal end of the protruding part is
located at a position obliquely extended from the outer peripheral
side of the endless portion, so that the same effects as that of
the fifth embodiment can be expected.
[0079] FIG. 17 shows the seventh embodiment of the present
invention. In this case, a protruding part 22 is extended obliquely
from the entire peripheral side of endless portion 21 to one end
from which a curved portion is formed. A rounded projection is
formed swellingly at the distal end of the protruding part. A pair
of fitting ribs 23a and 23b having approximate triangular
cross-sections having different inclinations are projectively
formed side by side on the obverse surface at the inner side of
endless portion 21. In this case, the protruding part is extended
obliquely upwards from the endless portion with an angle of
inclination of 20.degree. to 60.degree., preferably 20.degree. to
45.degree., and continuously formed with the curved portion with a
rounded projection at the distal end, in a similar manner to that
of the sixth embodiment.
[0080] Further, the projected portion extended obliquely may have a
substantially uniform thickness of 0.6 to 1.5 mm at its proximal
side. It is further preferred that the projected portion is formed
so as to become gradually narrower toward the end. Also in this
case, the distal end of the protruding part is located at a
position obliquely extended from the outer peripheral side of the
endless portion, so that the same effects as that of the fifth
embodiment can be expected.
[0081] Now, examples of hermetic containers of the present
invention will be described together with comparative examples.
[0082] 1. Hermetic Container Sealability Confirmatory Test
EXAMPLE
[0083] A sealing element 20 formed in the shape as shown in FIGS. 4
to 6 was formed using fluororubber. This sealing element 20 was
fitted to a hermetic container for in-process transport, capable of
accommodating 25 sheets of 300 mm precision substrates (silicon
wafers) 2, and a sealability confirmatory test was carried out.
[0084] The confirmatory test was implemented in the manner as shown
in FIG. 18. Specifically, a flexible hose, namely a pipe 30, was
connected to a container body 1 having a passage hole drilled at
the lower site on the backside thereof and the joint between the
passage hole and pipe 30 was sealed with a sealant. Open front 9 of
container body 1 was fitted and closed with door element 11 with
sealing element 20 fitted thereon. A pressure gauge 31 was set in
pipe 30 while a pressure device 32 for pressurizing the interior of
the hermetic container and a pump for reducing the pressure inside
the hermetic container were joined via a gate valve to the distal
end of pipe 30. Then, changes in pressure were measured for the
case where the interior of the hermetic container was pressurized
(plus 2.times.10.sup.4 Pa) and then gate valve 33 closed and for
the case where the interior of the hermetic container was evacuated
(minus 2.times.10.sup.4 Pa) and then gate valve 33 closed, were
measured by pressure gauge 31 to check the sealability. The result
is shown in Table 1.
COMPARATIVE EXAMPLE
[0085] A sealing element 20 formed in the shape shown in FIG. 1 was
formed using fluororubber, and the same confirmatory test as the
example was implemented. The result is shown in Table 1.
1 TABLE 1 -2 .times. 10.sup.4 Pa plus 2 .times. 10.sup.4 Pa (when
evacuated) (when pressurized) Example -9 .times. 10.sup.3 Pa 0 Pa
after 10 min. after 20 sec. Comparative -2 .times. 10.sup.3 Pa 0 Pa
Example after 10 min. instantly
[0086] 2. Measurement of the Repulsive Force of Sealing
Elements
EXAMPLE
[0087] A 3 cm sample of linear section was cut from the sealing
element 20 used in the sealability confirmatory test and the amount
of squeezing and its repulsive force when this sample was pressed
were measured by a precision universal tester (a trade name:
Autograph, a product of SHIMADZU CORPORATION). The result is shown
in Table 2.
COMPARATIVE EXAMPLE
[0088] Similarly to the example, a sample of 3 cm linear section
was cut from the sealing element 20 used in the sealability
confirmatory test and the amount of squeezing and its repulsive
force when this sample was pressed were measured by the precision
universal tester. The result is shown in Table 2.
2 TABLE 2 Repulsive Force (N/cm) Amount of Squeezing (mm) 0.5 1.0
1.5 Example 0.12 0.19 0.19 Comparative Example 0.94 0.94 1.46
[0089] As has been described, according to the present invention,
it is possible to substantially uniformly seal the inner periphery
of the opening face of the container body. Further, it is possible
to prevent items from being contaminated without causing any
interrupts during the operation of the door element and without any
loss of sealability due to repeated opening and closing actions.
Moreover, even when being washed with the container body or door
element, the sealing element can be washed well so as to improve
the cleansability and drainage and the time needed for drying can
be reduced.
* * * * *